Current mobile wireless networks usually comprise a core network with network nodes which handle traffic for a mobile device or user equipment. When a mobile device is setting up or modifying connections, core network nodes for handling the connections generally need to be selected. For example, in an Evolved Packet System (EPS) network, a Serving Gateway (SGW) and a Packet Data Network (PDN) Gateway (PGW) are selected when the mobile device/user equipment (UE) attaches or establishes a new connection to a PDN. A connection modification may for example be the selection of a new SGW if a mobile device moves to a different SGW service area. Corresponding selection mechanisms can be employed in other wireless networks, such as in Global Systems for Mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access (CDMA), or wide band-CDMA (W-CDMA) networks.
Constrains that limit the selection of these network nodes include for example the ability of the SGW to serve the tracking area, in which the mobile device is located, or the ability of the PGW to provide connectivity to the PDN, with which the mobile device requests to communicate. Similarly, in a GPRS (General Packet Radio Service) core network, the Serving GPRS Support Node (SGSN) may select a Gateway GPRS Support Node (GGSN) which provides connectivity to the network identified by a requested Access Point Name (APN). In general, several core network nodes will meet these constrains. The selection of one of these suitable nodes for handling the connection has a substantial impact on the efficiency of data transport to the mobile device.
A conventional method for selecting an appropriate core network node is described in the 3GPP technical specification 29.303, which can be obtained at http://www.3gpp.org/ftp/Specs/html-info/29303.htm. The method uses the so-called “topological proximity” as a criteria, and bases the selection on the longest-suffix-match of node names. This method is also referred to as “topon” mechanism. The mechanism is based on the naming of EPC network nodes according to a naming scheme that represents a tree structure. Two nodes are considered closer to each other if they share a longer common name “root” or “suffix”. As the transport efficiency is generally higher if the network nodes are located closer together, the mechanism may select two network nodes, e.g. an SGW and an PGW, sharing the longest name suffix.
Such a selection mechanism has a fundamental problem, which will be illustrated by the following example. A first SGW may be named “SGW1.region3.west.vfe.mycom.”, a first PGW may be named “PGW1.region7.west.vfe.mycom.”, and a second PGW may be named “PGW2.north.vfe.mycom.”. The mechanism would now select the first SGW and the first PGW, as they share the longer suffix “west.vfe.mycom” compared to the combination of the first SGW and the second PGW. If geographical terms like “north” and “west” are used in the names, this appears to be a good mechanism to judge the proximity between the network nodes. Yet such a mechanism has a major disadvantage. The first SGW may for example be a node in Portland, Oreg. at the USA West Coast, whereas the first PGW may be located in San Diego, Calif., at the USA West Coast. The second PGW may be located in Seattle, Wash., a USA north state. SGW1 and PGW1, which would have been selected by the topon mechanism, have a distance of 1802 miles, whereas SGW1 and PGW2 have a distance of only 176 miles from each other. Such a selection mechanism will accordingly result in an inefficient data transport for the above example. Even if a different name scheme was used, the problem would still be existent at borders of areas or regions of such a naming scheme.
One problem with such a mechanism is that a naming structure and roots based on a longest suffix match can only represent tree like structures. Yet an IP network generally represents a much more complex graph than a simple tree structure. Naming schemes such as the Domain Name System (DNS) are unable to handle the actual topology of an IP network. Nodes located closed to each other may have relatively short matching name suffixes, or nodes located closed to each other with a longer matching suffix may not be directly connected to each other, i.e. may only communicate via other nodes over a longer network path.
Another possibility to overcome the problem mentioned above would be the using of DNS records in combination with information on the GPS coordinates of each node. Even though the geographical distance between two nodes may be minimized that way, node selection may still result in a poor data transport efficiency, as again, the nodes may not be connected directly to each other. The traffic between the nodes may then need to be routed via other nodes and might follow a much longer path than the actual geographical distance between them.
It is desirable to perform the selection of core network nodes so as to enable a higher data transport efficiency. Accordingly, there is a need to improve the selection of a network node for handling data traffic for a mobile device.